locking knees and elbows

[Soeren Nielsen]

it is possible to create such a rig. is a serious pain tho. You cant dynamicly pin objects in XSI, but you can always set up a position constraint for your knees and elbows, and animate the weight of those. Its not the same, but the effect will be close to the same.

[ThE_JacO]

if you are using IK you can't simply constrain a middle joint.

all you need to do is blend/switch to FK and work on from there, easiest, simpliest and most common way to do it, especially for arms.

[Soeren Nielsen]

true Jaco, if you dont break your chain you cant set up a constraint. And as you say using FK/IK blending is faster and easier :) but not what he was asking for ;) .. uh well, Ill just go poke something

[ThE_JacO]

if you break up the chain into subchains then you are giving up the native IK.
on my current job, for a very versatile quadruped rig I had to setup, I ended up (and that's just for a footlock on the 3rd and 4th join of a front paw) having to write my own derivative motion algorithm to simulate 3 chains IK behaviors (on a 4bones chain) without all the problems involved in having a short flipped bone at the end.

if you split to lock you either have to write the expected derivative/interpolated motion yourself or work with a risky constraints setup.
the alternative is playing with animatable pseudoroot state or stiffness, but it can lead to other nasty results you most def don't want in a biped rig.

for bipeds (and I assume it's one since arms are involved) 2bones IK to the ankle + footroll and an FK blending is the most desireable setup in 99% of the situations.
Arms you could as well want to have them all FK most of the time, possibly with split rotation nulls at the shoulder root, and blend in IK only for simple and casual motion or walk/run cycles and objects grabbing.

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